The invention relates to a universal waveguide joint, provided with at least two waveguide segments slidable over each other, to a flexible waveguide coupler derived from the universal waveguide joint in an embodiment according to the invention, and to an arrangement for a surveillance radar antenna, in which arrangement the flexible waveguide coupler finds specific application according to the invention.
Universal waveguide joints are of prior art; in EP-A- No. 0.147.900, FIG. 4 depicts a waveguide joint, in which the combination of several waveguide segments is so arranged that through the use of two stepped twisters the input waveguide segment is movable relatively to the output waveguide segment about two mutually perpendicular axes lying in a plane perpendicular to the direction in which further waveguides are connected to the universal waveguide joint.
A universal waveguide joint may be incorporated in an arrangement for a vehicle- or vessel-borne surveillance radar antenna, provided with a two-axis, gimbal system mounted on the vehicle or vessel, and with a platform suspended by the gimbal system, which platform can be stabilised about the mutually orthogonal axes of the gimbal system with respect to an earth-fixed reference position, whereby the surveillance radar antenna is mounted rotatably about an axis perpendicular to the platform, while a mechanical, universal joint transmits the rotational motion produced by a drive mechanism, mounted directly on the vehicle or vessel, to the surveillance radar antenna; the universal waveguide joint is incorporated in the waveguide channel for transmitting the r.f. energy between a transmitting and receiving unit, mounted directly on the vehicle or vessel, and the antenna.
The orthogonal axes of both the mechanical and the universal waveguide joints are rotatable in the plane through the axes of the gimbal system. In the surveillance radar antenna arrangement described in the cited patent publication the waveguide channel including the universal waveguide joint bypasses the mechanical joint entirely, whereby the universal waveguide joint takes up relatively much space. Consequently the gimbal system, by which the platform is suspended, is of a relatively large size and hence of a heavy construction.